Rotary lawn mowers are known which comprise a mower housing, a rigid cutting blade rotatable in a cutting chamber in the housing and a traction drive for self-propelling the mower housing over the ground. Such machines may have a dead-man's control for operating the traction drive. Such a control is offered on certain lawn mowers manufactured by The Toro Company, Minneapolis, Minn., the assignee of the present invention. This type of control usually comprises a pivotally mounted control bar carried on the handle assembly of the mower. Whenever the operator releases the bar, the control bar falls to a neutral position in which the traction drive is disengaged.
Lawn mowers which use a rigid steel blade as the cutting element present a safety problem. Such a blade when rotating is capable of doing injury to the operator. Operators have had fingers or toes injured or severed by this type of blade. Such accidents will occur either due to the carelessness of the operator or by virtue of an unforeseen set of circumstances leading to the injury. It is, therefore, desirable that any lawn mower having a rigid cutting element such as a blade be equipped with a blade brake clutch for stopping the cutting blade whenever it poses a danger to the operator. Some prior art lawn mowers have been equipped with such blade brake clutches. In addition, some of these lawn mowers used a dead-man's control for actuating the blade brake clutch.
To the best of Applicant's knowledge every lawn mower having both a traction drive and a blade brake clutch has utilized two separate dead-man's controls for actuating these two elements individually. This is duplicative of materials and, therefore, relatively expensive. Moreover, it also presents two separate controls each of which must be manually actuated by the operator to get both the traction drive function and rotation of the cutting blade. This may be confusing and cumbersome to some operators.
Moreover, a simple pivotal dead-man's control can be actuated in only one single uninterrupted motion. This is disadvantageous since it is conducive to inadvertent actuation of the control. Instead, it would be preferable that two separate actions must be performed on the control member in order to obtain blade rotation.
Certain lawn mower are known in which the cutting blade is directly connected to the drive motor shaft and the drive motor is simply started, often using an electric starting system, to achieve blade rotation. Some of these mowers use a brake to stop blade rotation by braking the drive motor shaft when the drive motor is turned off. U.S. Pat. No. 3,228,177 is an example of a mower of this type using a dead-man's control for actuating the brake and an engine kill switch which positively kills the ignition process in the drive motor when the control is released. Thus, dead-man's controls can be used both with a conventional clutch which selectively couples the blade to the rotating shaft of the drive motor and also with a clutch in the sense of a blade coupled to a drive motor which is started and stopped to get blade rotation. Both types of clutches often utilize brakes to positively stop the cutting blade.